While nations concede a pressing need for attacking carbon dioxide emissions, other pollutants offer quicker paybacks. Four pollutants that make a relatively brief but powerful appearance in the atmosphere are known as the short-lived climate warmers: methane, near-surface ozone, a class of industrial chemicals called hydrofluorocarbons and the black-carbon component of soot. A growing number of climate scientists say the quickest way to stall Earth's slowly rising fever in the short term is to reduce the output of these more ephemeral warmers. [Source: ScienceNews]